There’s a new bug (feature?) in Facebook that prevents using more than 12 friend lists in many areas of the website. It’s highly frustrating.
If you run into this situation where you want to filter your friends but can’t see the list you need, there is only one workaround:
You have to send your infrequently used friend lists to the bottom of the pile by renaming them. You can do this by going to the lists page, opening one of your lists, clicking “Manage List” in the upper-right corner, and then selecting Rename.
The list is sent to the bottom by pre-pending a “Z” to the name. For example,
Z Annoying People
Unfortunately, this doesn’t work at all for Smart Lists, such as for work or college friends. If those lists aren’t showing up, you’re better off re-creating them from scratch as custom friend lists. Smart Lists are effectively useless for anything other than adjusting privacy settings.
As usual, Facebook offers no way to report this type of bug, and everyone will be stuck with using workarounds for a long time.